[PATCH v8 03/11] gpio: add ti-ssp gpio driver

[Cyril Chemparathy <cyril-l0cyMroinI0@public.gmane.org>]

TI's SSP controller pins can be directly read and written to behave like a
GPIO.  This patch adds a GPIO driver that exposes such functionality.

Signed-off-by: Cyril Chemparathy <cyril-l0cyMroinI0@public.gmane.org>
---
 drivers/gpio/Kconfig       |   10 ++
 drivers/gpio/Makefile      |    1 +
 drivers/gpio/ti-ssp-gpio.c |  207 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/mfd/ti_ssp.h |    4 +
 4 files changed, 222 insertions(+), 0 deletions(-)
 create mode 100644 drivers/gpio/ti-ssp-gpio.c

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 3143ac7..05bbe4c 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -128,6 +128,16 @@ config GPIO_VX855
 	  additional drivers must be enabled in order to use the
 	  functionality of the device.
 
+config GPIO_TI_SSP
+	tristate "TI Sequencer Serial Port - GPIO Support"
+	depends on MFD_TI_SSP
+	help
+	  Say yes here to support a GPIO interface on TI SSP port pins.
+	  Each SSP port translates into 4 GPIOs.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called ti-ssp-gpio.
+
 comment "I2C GPIO expanders:"
 
 config GPIO_MAX7300
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index bdf3dde..0e2a844 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -26,6 +26,7 @@ obj-$(CONFIG_GPIO_PL061)	+= pl061.o
 obj-$(CONFIG_GPIO_STMPE)	+= stmpe-gpio.o
 obj-$(CONFIG_GPIO_TC35892)	+= tc35892-gpio.o
 obj-$(CONFIG_GPIO_TIMBERDALE)	+= timbgpio.o
+obj-$(CONFIG_GPIO_TI_SSP)	+= ti-ssp-gpio.o
 obj-$(CONFIG_GPIO_TWL4030)	+= twl4030-gpio.o
 obj-$(CONFIG_GPIO_UCB1400)	+= ucb1400_gpio.o
 obj-$(CONFIG_GPIO_XILINX)	+= xilinx_gpio.o
diff --git a/drivers/gpio/ti-ssp-gpio.c b/drivers/gpio/ti-ssp-gpio.c
new file mode 100644
index 0000000..edc3142
--- /dev/null
+++ b/drivers/gpio/ti-ssp-gpio.c
@@ -0,0 +1,207 @@
+/*
+ * Sequencer Serial Port (SSP) based virtual GPIO driver
+ *
+ * Copyright (C) 2010 Texas Instruments Inc
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/gpio.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/ti_ssp.h>
+
+struct ti_ssp_gpio_chip {
+	struct gpio_chip		chip;
+	struct device			*dev;
+	spinlock_t			lock;
+	u8				out;
+	u32				iosel;
+};
+
+#define to_ssp_gpio_chip(c) container_of(c, struct ti_ssp_gpio_chip, chip)
+
+static int ti_ssp_gpio_dir_in(struct gpio_chip *chip, unsigned gpio_num)
+{
+	struct ti_ssp_gpio_chip *gpio = to_ssp_gpio_chip(chip);
+	int error = 0;
+
+	spin_lock(&gpio->lock);
+
+	gpio->iosel &= ~SSP_PIN_MASK(gpio_num);
+	gpio->iosel |=  SSP_PIN_SEL(gpio_num, SSP_IN);
+
+	error = ti_ssp_set_iosel(gpio->dev, gpio->iosel);
+
+	spin_unlock(&gpio->lock);
+
+	return error;
+}
+
+static int ti_ssp_gpio_dir_out(struct gpio_chip *chip, unsigned gpio_num,
+			       int val)
+{
+	struct ti_ssp_gpio_chip *gpio = to_ssp_gpio_chip(chip);
+	int error;
+
+	spin_lock(&gpio->lock);
+
+	gpio->iosel &= ~SSP_PIN_MASK(gpio_num);
+	gpio->iosel |=  SSP_PIN_SEL(gpio_num, SSP_OUT);
+
+	error = ti_ssp_set_iosel(gpio->dev, gpio->iosel);
+
+	if (error < 0)
+		goto error;
+
+	if (val)
+		gpio->out |= BIT(gpio_num);
+	else
+		gpio->out &= ~BIT(gpio_num);
+
+	error = ti_ssp_raw_write(gpio->dev, gpio->out);
+
+error:
+	spin_unlock(&gpio->lock);
+	return error;
+}
+
+static int ti_ssp_gpio_get(struct gpio_chip *chip, unsigned gpio_num)
+{
+	struct ti_ssp_gpio_chip *gpio = to_ssp_gpio_chip(chip);
+	int ret;
+
+	spin_lock(&gpio->lock);
+
+	ret = ti_ssp_raw_read(gpio->dev);
+	if (ret >= 0)
+		ret = !!(ret & BIT(gpio_num));
+
+	spin_unlock(&gpio->lock);
+	return ret;
+}
+
+static void ti_ssp_gpio_set(struct gpio_chip *chip, unsigned gpio_num, int val)
+{
+	struct ti_ssp_gpio_chip *gpio = to_ssp_gpio_chip(chip);
+
+	spin_lock(&gpio->lock);
+
+	if (val)
+		gpio->out |= BIT(gpio_num);
+	else
+		gpio->out &= ~BIT(gpio_num);
+
+	ti_ssp_raw_write(gpio->dev, gpio->out);
+
+	spin_unlock(&gpio->lock);
+}
+
+static int __devinit ti_ssp_gpio_probe(struct platform_device *pdev)
+{
+	const struct ti_ssp_gpio_data *pdata = pdev->dev.platform_data;
+	struct device *dev = &pdev->dev;
+	struct ti_ssp_gpio_chip *gpio;
+	int error;
+
+	if (!pdata) {
+		dev_err(dev, "platform data not found\n");
+		return -EINVAL;
+	}
+
+	gpio = kzalloc(sizeof(*gpio), GFP_KERNEL);
+	if (!gpio) {
+		dev_err(dev, "cannot allocate driver data\n");
+		return -ENOMEM;
+	}
+
+	gpio->dev = dev;
+	gpio->iosel = SSP_PIN_SEL(0, SSP_IN) | SSP_PIN_SEL(1, SSP_IN) |
+		      SSP_PIN_SEL(2, SSP_IN) | SSP_PIN_SEL(3, SSP_IN);
+	error = ti_ssp_set_iosel(gpio->dev, gpio->iosel);
+	if (error < 0) {
+		dev_err(dev, "gpio io setup failed (%d)\n", error);
+		goto error;
+	}
+
+	spin_lock_init(&gpio->lock);
+	platform_set_drvdata(pdev, gpio);
+
+	gpio->chip.base  = pdata->start;
+	gpio->chip.ngpio = 4;
+	gpio->chip.dev   = &pdev->dev;
+	gpio->chip.label = "ti_ssp_gpio";
+	gpio->chip.owner = THIS_MODULE;
+	gpio->chip.get   = ti_ssp_gpio_get;
+	gpio->chip.set   = ti_ssp_gpio_set;
+	gpio->chip.direction_input  = ti_ssp_gpio_dir_in;
+	gpio->chip.direction_output = ti_ssp_gpio_dir_out;
+
+	error = gpiochip_add(&gpio->chip);
+	if (error < 0) {
+		dev_err(dev, "gpio chip registration failed (%d)\n", error);
+		goto error;
+	}
+
+	dev_info(dev, "ssp gpio interface registered\n");
+	return 0;
+
+error:
+	kfree(gpio);
+	return error;
+}
+
+static int __devexit ti_ssp_gpio_remove(struct platform_device *pdev)
+{
+	struct ti_ssp_gpio_chip *gpio = platform_get_drvdata(pdev);
+	int error;
+
+	error = gpiochip_remove(&gpio->chip);
+	if (error < 0)
+		return error;
+	kfree(gpio);
+	return 0;
+}
+
+static struct platform_driver ti_ssp_gpio_driver = {
+	.probe		= ti_ssp_gpio_probe,
+	.remove		= __devexit_p(ti_ssp_gpio_remove),
+	.driver		= {
+		.name	= "ti-ssp-gpio",
+		.owner	= THIS_MODULE,
+	},
+};
+
+static int __init ti_ssp_gpio_init(void)
+{
+	return platform_driver_register(&ti_ssp_gpio_driver);
+}
+module_init(ti_ssp_gpio_init);
+
+static void __exit ti_ssp_gpio_exit(void)
+{
+	platform_driver_unregister(&ti_ssp_gpio_driver);
+}
+module_exit(ti_ssp_gpio_exit);
+
+MODULE_DESCRIPTION("GPIO interface for TI-SSP");
+MODULE_AUTHOR("Cyril Chemparathy <cyril-l0cyMroinI0@public.gmane.org>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:ti-ssp-gpio");
diff --git a/include/linux/mfd/ti_ssp.h b/include/linux/mfd/ti_ssp.h
index dbb4b43..10c65bb 100644
--- a/include/linux/mfd/ti_ssp.h
+++ b/include/linux/mfd/ti_ssp.h
@@ -38,6 +38,10 @@ struct ti_ssp_spi_data {
 	void		(*select)(int cs);
 };
 
+struct ti_ssp_gpio_data {
+	int		start;
+};
+
 /*
  * Sequencer port IO pin configuration bits.  These do not correlate 1-1 with
  * the hardware.  The iosel field in the port data combines iosel1 and iosel2,
-- 
1.7.1


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